• JSTS:Journal of Semiconductor Technology and Science
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• v.9 no.1
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• pp.67-74
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• 2009

Monte Carlo simulation is widely used for predicting ion implantation profiles in amorphous targets. Here, we compared Monte Carlo simulation results with a vast database of ion implantation secondary ion mass spectrometry (SIMS), and showed that the Monte Carlo data sometimes deviated from the experimental data. We modified the electron stopping power model, calibrated its parameters, and reproduced most of the database. We also demonstrated that Monte Carlo simulation can accurately predict profiles in a low energy range of around 1keV once it is calibrated in the higher energy region.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.3
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• pp.18-27
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• 1998

Molecular dynamicsinvestigations of ion implantation considering point defect generation were performed with ion energies in the range of ~1keV, Simulation starts perfect diamond cubic lattice site. Stillinger-Weber potential and ZBL potential were used to calculate forces between atoms. We have simulated slowing-down of ion velocity, ion trajectory and coupled-coing between ion and silicon. We also discussed distribution of point defect using rdial distribution function. We found that interstitial produced by ion bombardment mainly formed interstitial cluster.

• Journal of Korean Society on Water Environment
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• v.22 no.4
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• pp.626-631
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• 2006

The adsorption features of copper ion have been investigated by taking the barley residue which occurring from the beer production process as an adsorbent. Under the experimental conditions, adsorption equilibrium of copper ion was attained within 30 minutes after the adsorption started and the adsorption reaction was observed to be first order. As the temperature increased, the adsorbed amount of copper ion at equilibrium was also increased, which indicated that the adsorption reaction was endothermic. Based on the experimental results which obtained by varying the temperatures, several thermodynamic parameters for copper adsorption reaction were estimated. Regarding the electrokinetic behavior of barley residue, its electrokinetic potential was observed to be positive below pH 5 and turned into negative above this pH. In the pH range from 1.5 to 4, copper adsorption was found to be increased, which was well explained by the electrokinetic behavior of barley residue in the pH range. When nitrilotriacetic acid, which is a complexing agent, was coexisted with copper ion, equilibrium adsorption of copper ion was decreased and this was presumed to be due to the formation of metal complex. In addition, the adsorbed amount of copper ion was examined to be increased when $KNO_3$ was coexisted, however, it approached a saturated value above a certain concentration of $KNO_3$.

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.177-181
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• 2004

A PVC membrane electrode for silver ion based on a new cone shaped calix[4]arene (CASCA) as membrane carrier was prepared. The electrode exhibits a Nernstian response for $Ag^+$ over a wide concentration range ($1.0{\times}10^{-1}-8.0{\times}10^{-6}$M) with a slope of 58.2 {\pm}$ 0.5 mV per decade. The limit of detection of the sensor is $5.0{\times}10^{-6}$M. The sensor has a very fast response time (~5 s) in the concentration range of ${\leq}=1.0{\times}10^{-3}$ M, and a useful working pH range of 4.0-9.5. The proposed sensor displays excellent discriminating ability toward $Ag^+$ ion with respect to common alkali, alkaline earth, transition and heavy metal ions. It was used as an indicator electrode in potentiometric titration of $Ag^+$ with EDTA and in direct determination of silver ion in wastewater of silver electroplating.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4209-4214
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• 2022

Precise modelling of the interaction of ions with materials is important for many applications including material characterization, ion implantation in devices, thermonuclear fusion, hadron therapy, secondary particle production (e.g. neutron), etc. In this study, a new approach using the Geant4 toolkit in combination with the Bayesian regularization (BR) learning algorithm of the feed-forward neural network (FFNN) is developed to estimate the range of ions in materials accurately and quickly. The different incident ions at different energies are interacted with the target materials. The Geant4 is utilized to model the interactions and to calculate the range of the ions. Afterward, the appropriate architecture of the FFNN-BR with the relevant input features is utilized to learn the modelled ranges and to estimate the new ranges for the new cases. The notable achievements of the proposed approach are: 1- The range of ions in different materials is given as quickly as possible and the time required for estimating the ranges can be neglected (i.e. less than 0.01 s by a typical personal computer). 2- The proposed approach can generalize its ability for estimating the new untrained cases. 3- There is no need for a pre-made lookup table for the estimation of the range values.

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.629-633
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• 2004

A new PVC membrane electrode for $UO_2^{2+}$ ion based on 2,2'-[1,2-ethanediyl bis (nitriloethylidene)]bis(1-naphthalene) as a suitable ionophore was prepared. The electrode exhibites a Nernstian response for $UO_2^{2+}$ ion over a wide concentration range ($1.0{\times}10^{-1}-1.0{\times}10^{-7}$M) with a slope of 28.5 ${\pm}$ 0.8 mV/decade. The limit of detection is $7.0{\times}10^{-8}$M. The electrode has a response time of < 20 s and a useful working pH range of 3-4. The proposed membrane sensor shows good discriminating abilities towards $UO_2^{2+}$ ion with regard to several alkali, alkaline earth transition and heavy metal ions. It was successfully used to the recovery of uranyl ion from, tap water and, as an indicator electrode, in potentiometric titration of $UO_2^{2+}$ ion with Piroxycam.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.30-30
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• 2003

Without a definitive resolution of stoichiometry of cardiac Na$^{+}$-Ca$^{2+}$exchange (NCX), we cannot proceed to any quantitative analysis of exchange function as well as cardiac excitation-contraction coupling. The stoichiometry of cardiac NCX, however, is presently in doubt because reversal potentials determined by various groups range between those expected for a 3-to-1 and a 4-to-1 flux coupling. For a new perspective on this problem, we have used ion-selective microelectrodes to quantify directly exchanger-mediated fluxes of $Ca^{2+}$and Na$^{+}$in giant membrane patches. $Ca^{2+}$- and Na$^{+}$-selective microelectrodes, fabricated from quartz capillaries, are placed inside of the patch pipettes to detect extracellular ion transients associated with exchange activity. Ion changes are monitored at various distances from the membrane, and the absolute ion fluxes through NCX are determined via simulations of ion diffusion and compared with standard ion fluxes (Ca$^{2+}$ fluxes mediated by $Ca^{2+}$ ionophore, and Na$^{+}$ fluxes through gramicidin channels and Na$^{+}$/K$^{+}$pumps). Both guinea pig myocytes and NCX1-expressing BHK cells were employed, and for both systems the calculated stoichiometries for inward and outward exchange currents range between 3.2- and 3.4-to-1. The coupling ratios do not change significantly when currents are varied by changing cytoplasmic [Ca$^{2+}$] or by adding cytoplasmic Na$^{+}$. The exchanger reversal potentials, measured in both systems under several ionic conditions, range from 3.1- to 3.3-to-1. Taken together, a clear discrepancy from a NCX stoichiometry of 3-to-1 was obtained. Further definitive experiments are required to acquire a fixed number, and the present working hypothesis is that NCX current has an extra current via ‘conduction mode’.ent via ‘conduction mode’.

• Journal of Energy Engineering
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• v.27 no.2
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• pp.70-80
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• 2018

Natural organic matter (NOM) is among the most common pollutant in underground and surface waters. It comprises of humic substances which contains anionic macromolecules such as aliphatic and aromatic compounds of a wide range of molecular weights along with carboxylic, phenolic functional groups. Although the concentration of NOM in potable water usually lies in the range of 1-10 ppm. Conventional treatment technologies are facing challenge in removing NOM effectively. The main issues are concentrated to low efficiency, membrane fouling, and harmful by-product formation. Ion-exchangers can be considered as an efficient and economic pretreatment technology for the removal of NOM. It not only consumes less time for pretreatment but also resist formation of trihalomethanes (THMs), an unwanted harmful by-product. This article provides a comprehensive review of ion exchange processes for the removal of NOM.

• Journal of Korean Vacuum Science & Technology
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• v.1 no.1
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• pp.1-12
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• 1997

A new three-dimensional (3D) Monte Carlo ion implantation simulator, TRICSI, has been developed to investigate 3D mask effects in the typical mask structure for ion implantation into crystalline silicon. We present the mask corner and mask size effects of implanted boron range profiles, and also show the calculated damage distributions by applying the modified Kinchin-Pease equation in the single-crystal silicon target. The simulator calculates accurately and efficiently the implanted-boron range profiles under the relatively large implanted area, using a newly developed search algorithm for the collision partner in the single-crystal silicon. All of the typical implant parameters such as dose, tilt and rotation angles, in addition to energy can be used for the 3D simulation of ion implantation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.185-186
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• 2005

Intrinsic gettering is usually used to improve wafer quality which is an important factor for reliable ULSI devices. The two-step annealing method was adopted in order to investigate interactions between oxygens and secondary defects during oxygen precipitation process in lightly and heavily boron doped silicon wafers with high energy $^{11}B^+$ ion implantation. Secondary defects were inspected nearby the projected range by high resolution transmission electron microscopy. Oxygen pileup was measured in the vicinity of the projected range by secondary ion mass spectrometry for heavily boron doped silicon wafers.